Disposable absorbent articles such as diapers and adult incontinence products are well known in the art. Such disposable absorbent articles collect and retain urine and feces deposited thereon by the wearer. While a great deal of effort has been and still is spent against improving the handling of urine, relatively little has been done to improve the handling of feces, in particular when dealing with low or medium viscosity feces.
Feces can be discharged by the wearer over a wide range of amounts, number of occurrences, consistency, depending on the age (newborn to adults) or condition of the wearer (nutrition, sicknesses, etc.). It is said, that daily loadings can average between 100 gram to over 1000 g under pathologic conditions, with individual daily loadings being as low a 40 grams. The loading frequency is generally higher with small babies (newborn up to five occurrences per day), and decreasing with age to about once per day for adults. Composition is also very variable, but within the scope of the present invention the amount of water is of particular interest, which can range from about 70% to about 90% of total discharge. Correspondingly, the consistency of such discharges (often referred to a as "bowel movements" or abbreviated "BM") can range from "firm" over "pasty" to "runny". Within the scope of the present invention, this consistency can best be correlated with the technical measure of viscosity.
Obviously, the handling of such materials requires very different structures as compared to the structures for "storage" or absorbency of fluids like urine. For the latter, a much smaller pore sizes is required (which can be even as small as to molecular size, such as provided by "superabsorbent materials", though there in addition to other effects). Storage of feces however, requires sufficiently open/large pores for being able to receive the feces, which--in comparison to urine--have a much higher viscosity. This requirement applies both to the topsheet (facing) materials of an absorbent article, and also to materials which are supposed to store respective materials.
Attempts to improve the handling of feces include providing a first topsheet which conforms closely to the wearer and has an aperture. The aperture is hopefully registered with the anal opening, so that feces passes there through into a void space. The first topsheet may comprise various elastic panels in order to closely conform to the skin of the wearer, and/or may have linear elastic strands. Improvements have been made in this area of the prior art, such as optimizing the material properties of the first topsheet. Such optimization makes the first topsheet more comfortable to the wearer and allows a single disposable absorbent article to fit a larger range of sizes of wearers. Examples for such approaches are given in EP-A-0 359 410; EP-A-0 386 816; EP-A-0 644 747.
Further improvements to this type of the prior art disposable absorbent articles also include the addition of spacers. Spacers may be interposed between the first topsheet and the core, in order to ensure a void space is present to receive the feces. Examples for these approaches are given in U.S. Pat. No. 4,778,459; FR-2 495 899; WO 90/14063; WO 93/12748.
Yet other attempts have been made for such types of the prior art articles by providing barriers which limit the movement of feces to particular portions of the disposable absorbent article. The barriers limit the contact of the feces to a lesser portion of the skin of the wearer, than a comparable disposable absorbent article which has no barriers. Such approaches are disclosed in U.S. Pat. No. 5,514,121; EP-A-0 486 006.
However, none of these attempts to handle feces solve the specific problems which occur when feces of a softer consistency is present, such as being prevalent for younger children, particularly those who are breast fed. Such lower viscosity feces are referred to by mothers as "runny bowel movement (or BM)" corresponding to low-viscosity feces, or "pasty BM" for feces of a higher consistency, which however still has a much lower viscosity than "firm BM". Such lower viscosity feces easily migrate within the disposable absorbent article under the influences of gravity and motion or pressure by the wearer.
The migration of the feces often results in movement of it on the surface of the absorbent article towards the perimeter of the disposable absorbent article, increasing the likelihood of leakage. The migration of the feces also smears it against the skin of the wearer, making cleanup more difficult. In order to clean the wearer, the caretaker must wipe the entire area of the skin which has encountered the feces and typically has to deal with a relatively large soiled area.
One serious attempt in the art to handle low-viscosity feces is found in U.S. Pat. No. 5,342,338. This application describes a disposable absorbent article having a first topsheet with a high trans-topsheet penetration overlaying a secondary topsheet having a lesser trans-topsheet penetration.
PCT US 94/08958 discloses further a disposable absorbent article which reduces leakage of low-viscosity feces from the disposable absorbent article and aims at minimizing the amount of low-viscosity feces remaining on the skin of the wearer once the disposable absorbent article is removed by combining a topsheet with high trans-topsheet penetration and a fecal storage material.
However, the prior art referred to herein before is relying on in-use movements to create storage space, such as by allowing the topsheet to detach from the underlying fluid storage structure possibly enhanced by elastic features. Hence it is an object of the current invention, to provide such storage space from the beginning of the use period and to further maintain such storage space during use.
Hence it is an object of the invention to provide structures with improved feces handling properties especially for medium viscosity feces, as expressed by improved feces storage capacity.
It is a further object of the invention to allow selection of the appropriate materials for such improved structures by assessing the medium viscosity feces storage capacity, related to either the amount of material used or the area of the material.